The Annular-Total (or Hybrid) Solar Eclipse of 3 November 2013.
A Hybrid Eclipse occurs when the Moon is only just close enough to the Earth to give a Total Eclipse along some of the central path. At the edges, the Earth curves away from the Moon and the Moon is then too far to cover the Sun completely. At these points the eclipse is Annular (ring shaped) instead of Total.
The narrow blue region is the Path of Totality of the eclipse (also known as the Umbra).
The Moon's umbra (shadow) travels from west to east (left to right on the map). Only the first part of the path is annular, the majority of the track gives a total eclipse.
At the point of Greatest Eclipse, totality is at local midday. The duration of totality at greatest eclipse is 1 minute 40 seconds. This occured in the Atlantic Ocean. On either side of that point, the duration of totality is less. To the West (left) of the point of greatest eclipse, the eclipse is total before local noon; East (right) of this point, totality is seen after local noon. The umbra is generally widest around the time of greatest eclipse as the Earth is bulging out towards the Moon in that region. This brings the Earth's surface closer to the Moon.
The area on either side of the path of totality (in pale blue) is called the Penumbra and provides a partial eclipse, the magnitude decreasing with distance from the path of totality. Beyond the partial region no eclipse is visible.
The Sub-solar Point is the location where the Sun is overhead at the time of greatest eclipse; in November this point is South of the equator. The parts in red on either end of the umbra are the regions where the eclipse occurs during sunrise (left) or sunset (right).
The path of totality began in the Atlantic Ocean, off the coast of Florida (USA) with an annular eclipse at sunrise. It remained in the ocean for most of its journey across the Earth but quickly became total. The umbra only striked land late in the day. The umbra then crossed Gabon, Congo (both of them), Uganda, Kenya and Ethiopia.
The umbra left the Earth in Somalia at sunset.
The umbra took 3 hours 20 minutes to traverse its entire path of 13,600km, covering 0.09% of the Earth's surface.
27% of all solar eclipses are total. Hybrid eclipses make up less than 5% of all solar eclipses. Most hybrid eclipses (91%) begin as annular, become total and end as annular. This eclipse was of an extremly rare type of hybrid (5%) that begin as annular but end as total. The next eclipse of this type will be 17 October 2172.
The Path of Totality (the Moon's Umbra) is the double lined dark blue band moving across Africa from left to right.
The times are in UT (essentially GMT).
The eclipse occurs late in the day close to the time of sunset over Uganda.
The Moon's shadow takes about two minutes to cross this region.
The Path of Totality is the dark band moving from left to right.
The Umbra is very elliptical in this region as the Moon's shadow (a cone) is meeting the surface of the Earth at an angle.
The Umbra is 62km long and 18km wide giving a path width of 19km.
I was based in the Murchison Falls National Park (the green area south of the umbra). On eclipse day, my safari driver took me to the village of Pokwero on the Centre Line (blue). From there I got a lift to the eclipse site away from the crowds.
This is the Path of Totality passing North of the small town of Pakwach.
The duration of totality in the small village of Pokwero (about 12km north of Pakwach close to the Central Line in blue) was just 0m 22s.
The eclipse site (marked with a yellow X) was the sport ground of a small school close to the village of Pokwero which is along the road on the right.
| Date | 3 November 2013 |
| Location | Pokwero - North of Pakwach |
| Latitude | 2° 33' 22" N |
| Longitude | 31° 23' 59" E |
| Altitude | 660 m |
| Distance from Centre Line | about 200m |
| 1st Contact (UT + 3) | 16:06 |
| 2nd Contact | 17:22:18 |
| 3rd Contact | 17:22:40 |
| 4th Contact | 18:27 |
| Sunset | 18:36 |
| Duration of Totality | 0m 22s |
| Path Width | 19 km |
| Major Axis | 62 km |
| Minor Axis | 18 km |
| Direction of Shadow Approach | ~ 255° |
| Umbral Velocity | 3.188 km/s |
| Solar Altitude | 17° |
| Solar Azimuth | 253° |
| Position Angle: 2nd Contact | 99° |
| Position Angle: 3rd Contact | 274° |
| Gamma | 0.3272 |
| Diameter Ratio | 1.006 |
| Saros Details | 143 (23 / 72) |
The Location, Latitude, Longitude and Altitude (in metres) are for the observation site at Pokwero, a village approximately 12km north of the city of Pakwach in northern Uganda. We were at a school about 1.7km from the village centre. The figures were measured on Google Earth.
The Distance from Centre Line was estimated from Google Interactive maps provided by Fred Espenak and others.
First Contact is the beginning of the eclipse when the first "bite" appears on the Sun's disk; it is the beginning of the partial phase. Note that this was a very late eclipse as First Contact took place in the late afternoon. Second Contact is the beginning of totality. Third Contact is the end of totality. Fourth Contact is the end of the partial eclipse. The times are in local time which, for this eclipse, was UT + 3 (GMT plus three hours).
The Duration of the eclipse at the observation site was 0 minutes 22 seconds.
The Path Width is the width of the path of totality. The umbra itself was very elliptical in shape. The Major Axis is the longest axis of the umbra; the Minor Axis is the shorter axis. The umbra at the observation site was about 62km long and about 18km wide and produced a path width of just 19km.
The Direction of the Shadow indicates that the umbra approached the observation site from the West. The Umbral Velocity was the speed of the Moon's shadow at the observation site. This and the umbral width determined the duration of the total eclipse.
The Sun's Altitude is measured from the horizon; the Azimuth is the direction of the Sun measured clockwise from North. The figures are for mid-eclipse. The Position Angles indicate the exact position of the Sun's disk where the Moon covers and uncovers the Sun at the beginning and end of totality. These figures determined the position of any diamond rings at the beginning and end of totality.
Gamma determines how the Moon's shadow, if extended, would pass through the Earth. A Gamma of zero implies that the shadow would pass through the exact centre of the Earth. A Gamma of greater than 1 misses the Earth and no total eclipse would occur. A positive Gamma passes North of the Earth's centre; a negative Gamma passes South of the Earth's centre.
The value of Gamma for this eclipse was 0.3272. This means that the shadow passed about a third of the way North of the Earth's centre. This, combined with the fact that in November, the Southern Hemisphere is tilted well towards the Sun, produced an eclipse mainly in the Equatorial regions.
The Diameter Ratio determines how much bigger the Moon's apparent radius is than the Sun's. In this case, the Moon's radius was 1.006 that of the Sun's. A total eclipse can only occur if this figure is greater than 1. The Moon would then appear larger than the Sun and could cover it completely. If this figure was less than one a total eclipse could not occur because the Moon would appear smaller than the Sun.
For this eclipse at the eclispe site the Moon appears 0.6% larger than the Sun so it only just covers it to produce a total eclipse.
The Saros is a collection of eclipses belonging to a series. Each member of the series is followed by a similar eclipse approximately 18 years, 11 days and 8 hours later. This eclipse was a member of Saros number 143. It was the 23rd eclipse out of a total of 72 in the series.
The series began on 7 March 1617 with a small partial eclipse in the Arctic regions. This was followed by 9 partial eclispes of increasing magnitude as the Moon's shadow moved closer to the Earth's centre with each successive eclipse. On 24 June 1797, the Moon's shadow finally made contact with the Earth to give the first of 12 total eclipses. The longest of these occurred on 19 August 1887 with a duration of 3m 50s.
The final purely total eclipse of the Saros took place on 24 October 1995, an event Kryss and Talaat saw in India.
The 2003 eclipse was the first of 4 Hybrid eclipses as the Moon's distance from the Earth has been increasing during the Saros cycle. In a Hybrid eclipse, parts of the eclipse path are total and parts are annular.
The vast majority of Hybrid eclipses begin as annular become total and end as annular. The 2013 eclispe is of a rare type that began as annular and end as total.
The first of 26 Annular eclipses occurs on 16 December 2085. The series ends with 20 partial eclipses in the Antarctic regions, the final one occurring on 23 April 2897.
The entire series will last for 1280 years.
At any one time dozens of Saros series are in progress. Other eclipses will belong to different series.
